The rotational spectrum and molecular structure of the benzene–hydrogen chloride complex

Abstract

The microwave spectrum of the weakly bound complex benzene–HCl was studied in the gas phase using Fourier transform microwave spectroscopy carried out in a Fabry–Perot cavity with a pulsed supersonic nozzle as the molecular source. Several R-branch a-dipole transitions have been observed for benzene–H 35Cl, benzene–D 35Cl, benzene–H 37Cl, and benzene(d6)–H 35Cl. The spectrum was characteristic of a symmetric top, indicating that the time averaged displacement of the H and Cl atoms from the benzene C6 axis is zero. Deuterium substitution of HCl demonstrated that the acidic proton lies between the Cl atom and the benzene ring. The chlorine nuclear quadrupole coupling constant χClaa, was measured for all four isotopic species and is interpreted in terms of a projection of the chlorine quadrupole coupling constant in free HCl, averaged over two degenerate vibrational ground state bending modes involving the angles between the benzene C6 axis and the HCl bond axis. The spectroscopic constants for benzene–HCl are: aNumbers in parentheses represent one standard deviation in the fit.

Chemistry at Low Pressure and Low Temperature: Rotational Spectrum and Dynamics of Pyrimidine-Neon

“…For asymmetric top complexes in which the stretching coordinate is near-parallel to the inertial a axis, the stretching force constant (k s ) can be estimated by approximating the complex to a molecule made of two rigid parts, by using expressions such as Equation (2), in which the subscript D denotes a dimer quantity, m D is the pseudo diatomic reduced mass, R CM is the distance between the centers of mass of the monomers (3.337 for PRM-Ne), and D J is the centrifugal distortion constant. [3,27] …”

π-Electron “Donor-Acceptor” Complexes B⋅⋅⋅ClF and the Existence of the “Chlorine Bond”

“…Both benzene´´´HCl [30] and benzene´´Ć lF [31] exhibit symmetric-top-type rotational spectra in the vibrational ground state. In the case of benzene´´´ClF, observation of a satellite associated with a low-lying vibrationally excited state in the rotational spectrum and evidence of a strong Coriolis interaction between this state and the ground state led to the conclusion that the geometry of the observed complex is as shown in Figure 7.…”

Rotational Spectrum and Internal Dynamics of Tetrahydrofuran–Krypton

“…Therefore, the stretching force constant (k s ) was estimated by approximating the complex to a molecule made of two rigid parts. In the presence of several symmetry elements, Millen [21] and Read et al [22] derived Equation (4) for asymmetric top complexes in which the stretching coordinates are almost parallel to the inertial a-axis:…”